In the last decades the phenomena related to the erosion in materials have been intensively studied by the scientific community in order to understand why materials in time erode (and then eventually crumble). Specifically the research on materials subjected to ion beam irradiation has shown how the erosion processes lead on the formation of irregular surfaces in the first layers of the same material samples. The study of the formation of these structures fascinates the researchers since it has been observed to occur in every kind of material be it metal, ceramic, plastic or semiconductor. In other words, due to its universality, the microscopical erosion phenomenon with the formation of surface nanostructures, is the one for which, in the macroscale, every material, soft or tough, looses its surface mechanical properties. Ultimately this type of phenomena are also responsible for the creation of dust. Beyond this, it was also observed how, these structures under ion beam irradiation, tend to generate "self organizing" structures with specific shapes (squares and hexagons). Such fascinating aspect can open new possibilities of application in the many different industrial applications, be those in the nanotechnology sector, in the nanomechanics, in the semiconductor industry, in the surface formation processes needed in chemistry, aerospace and nuclear fusion applications.
This thesis will study in detail the theoretical work behind the surface formation under ion beam irradiation, and following the model history in the last decades, it will focus on the latest mathematical model that is able to successfully predict the nanostructure formation in materials. It will be shown that such model (for the ion beams hitting normally the studied samples) is the "modified Kuramoto-Sivashinsky equation" and it will be studied its solutions for the case of three very interesting materials like silicon, germanium and gallium antimonide. This work could open the study of surface nanostructure formation for every kind of material and for sure there exist "islands or regions" of stability also for other materials like the steels. Due to its universality the modified KS model has possibly endless applications (for example in Mechanical Engineering it could allow the massive cheap creation of surfaces useful for building extremely efficient heat exchangers).
|Advisor:||Allain, Jean Paul|
|Commitee:||Hassanein, Ahmed, Rusek, John, Tsoukalas, Lefteri|
|School Location:||United States -- Indiana|
|Source:||MAI 50/06M, Masters Abstracts International|
|Subjects:||Applied Mathematics, Nuclear engineering, Materials science|
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